1. Field of the Invention
The present invention relates generally to an electron beam apparatus for focusing a primary beam on a specimen and, more particularly, to an arrangement for generating an electromagnetic field to promote extraction of secondary and/or backscatter electrons to a detector.
1. Description of the Prior Art
Electron beam devices are known having electrical extraction fields provided for secondary electrons. However, the known devices have a disadvantage in that the primary electron beam is influenced in its direction by the extraction field. This is particularly true when the primary beam is generated with a relatively low accelerating voltage of, for example, 1 kV.
An electron spectrometer is disclosed in Scanning Electron Microscopy, 1979/I, SEM, Inc., AMF O'Hare, Ill. 60606, USA, pp. 285-296.